JP5337725B2 - Automatic transmission - Google Patents

Description

  The present invention relates to an automatic transmission that shifts the rotation of an input shaft to a plurality of stages via a plurality of planetary gear mechanisms arranged in a transmission case and outputs the result from an output member.

  2. Description of the Related Art Conventionally, there has been known an automatic transmission that can perform eight forward speeds using a first planetary gear for input, two planetary gears for shifting, and six engagement mechanisms (for example, Patent Document 1).

  In Patent Document 1, a pair of first pinions in which a first planetary gear for input meshes with a first sun gear and a first ring gear, one meshes with the first sun gear and the other meshes with the first ring gear. Is constituted by a double pinion type planetary gear mechanism comprising a first carrier that pivotally supports and rotates freely.

  The first planetary gear decelerates the rotation speed of the first carrier, which is a fixed element that fixes the first sun gear to the transmission case, the input element that connects the first carrier to the input shaft, and the first carrier that serves as the input element. Output element to be

  Further, the two planetary gear mechanisms for shifting are engaged with the second sun gear, the third sun gear, and the second ring gear integrated with the third ring gear, and one of them is engaged with the second sun gear and the second ring gear. The other is composed of a Ravigneaux type planetary gear mechanism comprising a second carrier that pivotally supports and revolves a pair of second pinions meshing with the third sun gear.

  This Ravigneaux type planetary gear mechanism has a first rotation element and a second rotation in order with an interval corresponding to the gear ratio in a speed diagram (a ratio of relative speeds of the respective rotation elements can be represented by a straight line). When the element, the third rotating element, and the fourth rotating element are used, the first rotating element is the second sun gear, the second rotating element is the second carrier integrated with the third carrier, and the third rotating element is integrated with the third ring gear. The converted second ring gear and fourth rotation element become the third sun gear.

  Further, the engaging mechanism includes a first wet multi-plate clutch that releasably connects a first ring gear that is an output element of the first planetary gear and a fourth rotating element that is a third sun gear, an input shaft, and a second carrier. A second wet multi-plate clutch that releasably connects the second rotating element, and a third wet multi-plate clutch that releasably connects the first rotating element comprising the first ring gear and the second sun gear as output elements; A fourth wet multi-plate clutch for releasably connecting the first carrier as the input element and the first rotating element comprising the second sun gear, and the first rotating element comprising the second sun gear are releasably fixed to the transmission case. A first brake and a second brake for releasably fixing a second rotating element including the second carrier to the transmission case are provided.

  According to the above configuration, the first speed is established by engaging the first wet multi-plate clutch and the second brake, and the second speed is established by engaging the first wet multi-plate clutch and the first brake. A stage is established, and a third speed stage is established by engaging the first wet multi-plate clutch and the third wet multi-plate clutch, and the first wet multi-plate clutch and the fourth wet multi-plate clutch are engaged. This establishes the fourth gear.

  Further, the fifth speed stage is established by engaging the first wet multi-plate clutch and the second wet multi-plate clutch, and 6 by engaging the second wet multi-plate clutch and the fourth wet multi-plate clutch. By establishing the first gear, engaging the second wet multi-plate clutch and the third wet multi-plate clutch, the seventh gear is established, and by engaging the second wet multi-plate clutch and the first brake. The eighth gear is established.

  In the third wet multi-plate clutch of Patent Document 1, the hydraulic chamber for operating the piston is arranged on the axis of the input shaft, but the plurality of clutch plates pressed by the piston are the input first. It is arranged radially outward of the one planetary gear mechanism.

JP 2005-273768 A

  In the above-described conventional example, the number of engagement mechanisms engaged at each shift stage is two. Therefore, the friction loss due to dragging of the remaining four engagement mechanisms that are open increases, resulting in a problem that the efficiency of the automatic transmission deteriorates.

  Unlike the brake provided in the transmission case, the clutch is provided on the input shaft, the main shaft that supports the input shaft, and the like, and cannot be disposed radially outward of the planetary gear.

  Therefore, in the conventional example, a total of seven members including three planetary gear mechanisms and four clutches are arranged on the input shaft or on the main shaft that rotatably supports the input shaft. There is an inconvenience that the length becomes long and the mounting property to a vehicle (particularly, FF type vehicle) is low.

  In view of the above, an object of the present invention is to provide an automatic transmission that can reduce friction loss and can be mounted on a vehicle.

  [1] To achieve the above object, according to the present invention, an output member is provided by shifting the rotation of an input shaft that is rotatably supported in a transmission case and rotated by power from a drive source into a plurality of stages. The first to fourth planetary gear mechanisms each having three elements including a sun gear, a carrier, and a ring gear are provided, and the three elements of the first planetary gear mechanism are connected to a speed line. The first element, the second element, and the third element are arranged in the order corresponding to the gear ratio in the drawing, respectively, and the three elements of the second planetary gear mechanism are arranged in the speed chart corresponding to the gear ratio. The fourth element, the fifth element, and the sixth element are sequentially arranged, and the three elements of the third planetary gear mechanism are respectively arranged in the order corresponding to the gear ratio in the velocity diagram in the order of the seventh element and the eighth element. And the ninth element, and the three elements of the fourth planetary gear mechanism are arranged in the order of arrangement at intervals corresponding to the gear ratio in the velocity diagram, respectively, as the tenth element, the eleventh element, and the twelfth element. The eleventh element is coupled to the output member, the eleventh element is coupled to the output member, the first element and the fifth element are coupled to form a first coupling body, and the second element and the ninth element And the 12 elements are connected to form a second connected body, the fourth element and the 10th element are connected to form a third connected body, and the sixth element and the eighth element are connected. A first clutch that is connected to form a fourth connection body, and is switchable between a connection state in which the second connection body and the third element of the first planetary gear mechanism are connected, and an open state in which the connection is broken; Connected shape connecting the second connected body and the third connected body And a second clutch that can be switched to an open state that disconnects the connection, a first brake that can be switched to a fixed state in which the first connecting body is fixed to the transmission case, and an open state in which the fixing is released. A second brake that can be switched between a fixed state in which the fourth connecting body is fixed to the transmission case and an open state in which the fixation is released, and a seventh element of the third planetary gear mechanism. And a third brake that can be switched between a fixed state to be fixed to an open state and an open state to release the fixing.

  According to the present invention, as will be apparent from the description of the embodiment described later, it is possible to perform eight forward shifts and at each shift stage among a total of five engagement mechanisms of two clutches and three brakes. Two engagement mechanisms will be engaged. For this reason, the number of engagement mechanisms opened at each shift stage is three, and the friction loss due to the opened engagement mechanisms is reduced as compared with the conventional one where four engagement mechanisms are opened. The transmission efficiency of the automatic transmission can be improved.

  Further, four planetary gear mechanisms and two clutches are arranged on the axis of the input shaft, and a total of six members are arranged. For this reason, the axial length of the automatic transmission can be shortened as compared with the conventional product in which a total of seven members of three planetary gear mechanisms and four clutches are arranged on the axis of the input shaft, The mounting property to a vehicle (especially FF type vehicle) can be improved.

  [2] In the present invention, a one-way clutch that rotates integrally with the first coupling body only when the first coupling body reverses is provided, a fixed state in which the one-way clutch is fixed to the transmission case, and this fixing It is preferable to provide the 4th brake which can be switched to the open state which cancels | releases.

  According to this, as will be apparent from the description of the embodiment described later, the first brake can be constituted by a wet multi-plate brake having a relatively small capacity, and the friction loss can be further reduced. In addition, the controllability of the shift between the shift speeds can be improved. Moreover, the 1-way clutch can be disabled by opening the fourth brake. Thereby, the reverse gear can be established.

  [3] In the present invention, the first brake is a dog clutch or a reverse rotation preventing state in which forward rotation of the first coupling body is permitted and reverse rotation is prevented, and forward rotation of the first coupling body is prevented and reverse rotation is permitted. It is preferable to use a two-way clutch that can be switched to the forward rotation prevention state.

  According to this, the controllability of the shift is improved as will be apparent from the description of the embodiment described later. Further, in the open gear stage where the first coupling body is not fixed to the transmission case by the dog clutch or the 2-way clutch as the first brake, no friction loss occurs in the dog clutch or the 2-way clutch as the first brake. For this reason, the friction loss can be further reduced as the entire automatic transmission.

  [4] In the present invention, each of the four planetary gear mechanisms is constituted by a single-pinion type planetary gear mechanism including a sun gear, a ring gear, and a carrier that rotatably and revolves a pinion that meshes with the sun gear and the ring gear. It is preferable.

  According to this, the planetary gear mechanism is a double pinion type comprising a sun gear, a ring gear, and a carrier that rotatably and revolves a pair of pinions that mesh with each other and one meshes with the sun gear and the other meshes with the ring gear. Compared to the case of the planetary gear mechanism, the number of gear meshes in the power transmission path from the input shaft to the output member can be reduced, and the transmission efficiency can be improved.

The skeleton figure which shows the upper half of the automatic transmission of embodiment of this invention. The speed diagram which shows ratio of the relative speed of each element of the 1st-4th planetary gear mechanism of the automatic transmission of embodiment. Explanatory drawing which shows the connection and the fixed state of each engagement mechanism in every gear stage of the automatic transmission of embodiment.

  FIG. 1 shows an upper half of an embodiment of an automatic transmission according to the present invention. An automatic transmission according to this embodiment includes an input shaft 2 rotatably supported in a transmission case 1 and connected to a power source such as an engine (not shown), and an output gear arranged concentrically with the input shaft 2. The output member 3 which consists of these is provided. The rotation of the output member 3 is transmitted to the left and right drive wheels of the vehicle via a differential gear (not shown).

  In the transmission case 1, a first planetary gear mechanism 4, a second planetary gear mechanism 5, a third planetary gear mechanism 6, and a fourth planetary gear mechanism 7 are disposed concentrically with the input shaft 2. The first planetary gear mechanism 4 is composed of a single pinion type planetary gear mechanism that includes a sun gear Sa, a ring gear Ra, and a carrier Ca that rotatably and revolves a pinion Pa that meshes with the sun gear Sa and the ring gear Ra. Yes.

  Refer to the speed diagram of the first planetary gear mechanism 4 shown in the first stage (uppermost stage) from the top of FIG. 2 (the figure that can represent the ratio of the relative rotational speeds of the three elements of the sun gear, carrier, and ring gear as a straight line). Then, assuming that the three elements Sa, Ca, Ra of the first planetary gear mechanism 4 are the first element, the second element, and the third element from the left side in the order of arrangement at intervals corresponding to the gear ratio in the velocity diagram, respectively. The first element is a ring gear Ra, the second element is a carrier Ca, and the third element is a sun gear Sa.

  Here, the ratio between the distance between the sun gear Sa and the carrier Ca and the distance between the carrier Ca and the ring gear Ra is h: where the gear ratio of the first planetary gear mechanism 4 (number of teeth of the ring gear / number of teeth of the sun gear) is h: Set to 1. In the velocity diagram, the lower horizontal line and the upper horizontal line indicate that the rotational speeds are “0” and “1” (the same rotational speed as the input shaft 2), respectively.

  Similar to the first planetary gear mechanism 4, the second planetary gear mechanism 5 is a single gear comprising a sun gear Sb, a ring gear Rb, and a carrier Cb that rotatably and revolves a pinion Pb that meshes with the sun gear Sb and the ring gear Rb. It is composed of a pinion type planetary gear mechanism.

  Referring to the velocity diagram of the second planetary gear mechanism 5 shown in the second stage from the top in FIG. 2, the three elements Sb, Cb, Rb of the second planetary gear mechanism 5 are spaced at intervals corresponding to the gear ratio in the velocity diagram. If the fourth element, the fifth element, and the sixth element are respectively arranged from the left side in the order in which they are arranged, the fourth element is the sun gear Sb, the fifth element is the carrier Cb, and the sixth element is the ring gear Rb. The ratio between the distance between the sun gear Sb and the carrier Cb and the distance between the carrier Cb and the ring gear Rb is set to i: 1 where i is the gear ratio of the second planetary gear mechanism 5.

  Similar to the first and second planetary gear mechanisms 4 and 5, the third planetary gear mechanism 6 is a carrier Cc that supports the sun gear Sc, the ring gear Rc, and the pinion Pc that meshes with the sun gear Sc and the ring gear Rc so as to freely rotate and revolve. It consists of a single pinion type planetary gear mechanism.

  Referring to the speed diagram of the third planetary gear mechanism 6 shown in the third stage from the top in FIG. 2, the three elements Sc, Cc, Rc of the third planetary gear mechanism 6 are spaced at intervals corresponding to the gear ratio in the speed diagram. If the seventh element, the eighth element, and the ninth element are respectively arranged from the left side in the order in which they are arranged, the seventh element is the sun gear Sc, the eighth element is the carrier Cc, and the ninth element is the ring gear Rc. The ratio between the distance between the sun gear Sc and the carrier Cc and the distance between the carrier Cc and the ring gear Rc is set to j: 1 where j is the gear ratio of the third planetary gear mechanism 6.

  Similar to the first to third planetary gear mechanisms 4 to 6, the fourth planetary gear mechanism 7 is a carrier Cd that supports the sun gear Sd, the ring gear Rd, and the pinion Pd that meshes with the sun gear Sd and the ring gear Rd so as to rotate and revolve. It consists of a single pinion type planetary gear mechanism.

  Referring to the speed diagram of the fourth planetary gear mechanism 7 shown in the fourth stage (bottom stage) from the top in FIG. 2, the three elements Sd, Cd, Rd of the fourth planetary gear mechanism 7 are represented by the gear ratio in the speed diagram. If the tenth element, the eleventh element, and the twelfth element are arranged from the left side in the order of arrangement at intervals corresponding to, respectively, the tenth element is the sun gear Sd, the eleventh element is the carrier Cd, and the twelfth element is the ring gear Rd. The ratio between the distance between the sun gear Sd and the carrier Cd and the distance between the carrier Cd and the ring gear Rd is set to k: 1 where k is the gear ratio of the fourth planetary gear mechanism 7.

  The sun gear Sa (third element) of the first planetary gear mechanism 4 is connected to the input shaft 2. The carrier Cd (11th element) of the fourth planetary gear mechanism 7 is connected to the output member 3.

  Further, in the automatic transmission according to the embodiment, the ring gear Ra (first element) of the first planetary gear mechanism 4 and the carrier Cb (fifth element) of the second planetary gear mechanism 5 are coupled to each other, and the first coupling body Ra−. Cb is configured. In addition, the carrier Ca (second element) of the first planetary gear mechanism 4, the ring gear Rc (9th element) of the third planetary gear mechanism 6, and the ring gear Rd (12th element) of the fourth planetary gear mechanism 7 are connected to each other. A two-linked body Ca-Rc-Rd is configured.

  Further, the sun gear Sb (fourth element) of the second planetary gear mechanism 5 and the sun gear Sd (tenth element) of the fourth planetary gear mechanism 7 are connected to form a third connecting body Sb-Sd. Further, the ring gear Rb (sixth element) of the second planetary gear mechanism 5 and the carrier Cc (eighth element) of the third planetary gear mechanism 6 are connected to form a fourth connected body Rb-Cc.

  In the automatic transmission according to the embodiment, the first planetary gear Ra-Cb, the second linkage Ca-Rc-Rd, the sun gear Sa (third element) of the first planetary gear mechanism 4, and the first planetary gear mechanisms 4 to 7. A total of seven rotating bodies are constituted of the three linked bodies Sb-Sd, the fourth linked body Rb-Cc, the sun gear Sc (seventh element) of the third planetary gear mechanism 6 and the carrier Cd (eleventh element) of the fourth planetary gear mechanism 7. Has been.

  The automatic transmission according to the embodiment includes, as engagement mechanisms, first and second two wet multi-plate clutches C1 and C2, first to fourth four wet multi-plate brakes B1 to B4, 1 And a way clutch F1. The first wet multi-plate clutch C1 can be switched between a connected state in which the second connected body Ca-Rc-Rd and the sun gear Sa (third element) of the first planetary gear mechanism 4 are connected, and an open state in which this connection is cut off. It is configured.

  The second wet multi-plate clutch C2 is configured to be switchable between a connection state in which the second connection body Ca-Rc-Rd and the third connection body Sb-Sd are connected, and an open state in which the connection is broken. In other words, the second wet multi-plate clutch C2 is in a connected state in which the sun gear Sd (10th element) and the ring gear Rd (12th element) of the fourth planetary gear mechanism 7 are connected, and in an open state in which this connection is cut off. It is configured to be switchable.

  The first wet multi-plate brake B1 is configured to be switchable between a fixed state in which the first connecting body Ra-Cb is fixed to the transmission case 1 and an open state in which the fixing is released. The second wet multi-plate brake B2 is configured to be switchable between a fixed state in which the fourth connecting body Rb-Cc is fixed to the transmission case 1 and an open state in which this fixing is released.

  The third wet multi-plate brake B3 is configured to be switchable between a fixed state in which the sun gear Sc (seventh element) of the third planetary gear mechanism 6 is fixed to the transmission case 1 and an open state in which this fixing is released. . The fourth wet multi-plate brake B4 is configured to be switchable between a fixed state in which the 1-way clutch F1 is fixed to the transmission case 1 and an open state in which this fixing is released.

  The 1-way clutch F1 rotates integrally with the first coupling body Ra-Cb when the first coupling body Ra-Cb rotates in the reverse direction (rotation in the direction in which the vehicle moves backward), and the first coupling body Ra-Cb. Is configured to be rotatable relative to the first connecting body Ra-Cb without rotating integrally with the first connecting body Ra-Cb.

  In the automatic transmission according to the embodiment, when the first gear is established, the third wet multi-plate brake B3 and the fourth wet multi-plate brake B4 are set in a fixed state. As a result, the rotational speed of the sun gear Sc (seventh element) of the third planetary gear mechanism 6 becomes “0”, and the 1-way clutch F1 is fixed to the transmission case 1.

  The reverse rotation of the first coupling body Ra-Cb is prevented by the action of the 1-way clutch F1, and the rotation speed of the first coupling body Ra-Cb becomes “0”. Then, the rotational speed of the second coupling body Ca-Rc-Rd becomes 1 / (h + 1), and the rotational speed of the carrier Cd (11th element) of the fourth planetary gear mechanism 7 coupled to the output member 3 is shown in FIG. “1st” is reached and the first gear is established.

  At the first speed, the first wet multi-plate brake B1 is released, but the rotational speed of the first coupling body Ra-Cb becomes “0” by the action of the 1-way clutch F1, so the first wet multi-plate brake B1 is released. There is no friction loss in the plate brake B1. Further, if the first wet multi-plate brake B1 is fixed at the first speed, the engine brake can be applied.

  When the second gear is established, the second wet multi-plate brake B2 and the fourth wet multi-plate brake B4 are fixed. As a result, the rotational speed of the fourth coupling body Rb-Cc becomes “0”, and the rotational speed of the first coupling body Ra-Cb becomes “0” by the action of the 1-way clutch F1 fixed to the transmission case 1. become. Then, the rotational speed of the second coupling body Ca-Rc-Rd is 1 / (h + 1), the rotational speed of the third coupling body Sb-Sd is “0”, and the fourth planetary gear mechanism 7 coupled to the output member 3 The rotation speed of the carrier Cd (eleventh element) becomes “2nd” (k / {(h + 1) (k + 1)}) shown in FIG. 2, and the second gear is established.

  In the second speed stage, as in the case of the first speed stage, no friction loss occurs in the first wet multi-plate brake B1 that is in the released state. Even at the second speed, the engine brake can be applied if the first wet multi-plate brake B1 is set in a fixed state.

  When the third speed is established, the second wet multi-plate clutch C2 is brought into a connected state and the fourth wet multi-plate brake B4 is brought into a fixed state. As a result, the rotation speed of the first coupling body Ra-Cb becomes "0" by the action of the 1-way clutch F1 fixed to the transmission case 1, and the rotation speed of the second coupling body Ca-Rc-Rd is 1. / (H + 1).

  In addition, since the second coupling body Ca-Rc-Rd and the third coupling body Sb-Sd rotate at the same speed, the tenth to twelfth elements Sd, Cd, Rd of the fourth planetary gear mechanism 7 are relative to each other. The locked state becomes impossible to rotate, and the 10th to 12th elements Sd, Cd, Rd rotate at 1 / (h + 1). Therefore, the rotation speed of the carrier Cd (11th element) of the fourth planetary gear mechanism 7 connected to the output member 3 becomes “3rd” which is 1 / (h + 1), and the third speed stage is established.

  In the third speed, as in the case of the first and second speeds, no friction loss occurs in the first wet multi-plate brake B1 in the open state. Even at the third speed, if the first wet multi-plate brake B1 is in a fixed state, the engine brake can be applied.

  When the fourth speed is established, the second wet multi-plate clutch C2 is brought into a connected state, and the second wet multi-plate brake B2 and the fourth wet multi-plate brake B4 are brought into a fixed state. Thereby, since 2nd coupling body Ca-Rc-Rd and 3rd coupling body Sb-Sd rotate at the same speed, the 10th-12th three elements Sd, Cd, Rd of the 4th planetary gear mechanism 7 become The lock state is set so that relative rotation is impossible.

  Further, the rotational speed of the fourth coupling body Rb-Cc becomes “0”, and the rotational speed of the carrier Cd (11th element) of the fourth planetary gear mechanism 7 coupled to the output member 3 is “4th” ( (I + 1) / {i (h + 1) +1}), and the fourth gear is established.

  When the fifth speed is established, the second wet multi-plate clutch C2 is brought into a connected state, and the third wet multi-plate brake B3 and the fourth wet multi-plate brake B4 are brought into a fixed state. Thereby, since 2nd coupling body Ca-Rc-Rd and 3rd coupling body Sb-Sd rotate at the same speed, the 10th-12th three elements Sd, Cd, Rd of the 4th planetary gear mechanism 7 become The lock state is set so that relative rotation is impossible.

  Further, the rotation speed of the sun gear Sc (seventh element) of the third planetary gear mechanism 6 becomes “0”, and the rotation speed of the carrier Cd (11th element) of the fourth planetary gear mechanism 7 connected to the output member 3 is shown in FIG. 5th stage ({(i + 1) (j + 1)} / {(i + 1) (j + 1) + hi})) is established.

  When the sixth speed is established, the first wet multi-plate clutch C1 and the second wet multi-plate clutch C2 are connected, and the fourth wet multi-plate brake B4 is fixed. As a result, the second coupling body Ca-Rc-Rd and the sun gear Sa (third element) of the first planetary gear mechanism 4 rotate at the same speed, and the first to third elements Sa of the first planetary gear mechanism 4 are rotated. , Ca, Ra are in a locked state in which relative rotation is impossible, and the first to third elements Sa, Ca, Ra rotate by “1”.

  In addition, since the second coupling body Ca-Rc-Rd and the third coupling body Sb-Sd rotate at the same speed, the tenth to twelfth elements Sd, Cd, Rd of the fourth planetary gear mechanism 7 are also relative to each other. It becomes a locked state that cannot be rotated. Accordingly, the rotation speed of the carrier Cd (11th element) of the fourth planetary gear mechanism 7 connected to the output member 3 becomes “6th” which is “1”, and the sixth speed is established.

  When the seventh speed is established, the first wet multi-plate clutch C1 is brought into a connected state, and the third wet multi-plate brake B3 and the fourth wet multi-plate brake B4 are brought into a fixed state. As a result, the second coupling body Ca-Rc-Rd and the sun gear Sa (third element) of the first planetary gear mechanism 4 rotate at the same speed, and the first to third elements Sa of the first planetary gear mechanism 4 are rotated. , Ca and Ra are in a locked state where relative rotation is impossible. Thereby, the rotational speed of 1st coupling body Ra-Cb and 2nd coupling body Ca-Rc-Rd becomes "1".

  Further, the rotational speed of the sun gear Sc (seventh element) of the third planetary gear mechanism 6 is “0”, and the rotational speed of the fourth coupled body Rb-Cc is j / (j + 1). Then, the rotational speed of the carrier Cd (11th element) of the fourth planetary gear mechanism 7 connected to the output member 3 becomes “7th” shown in FIG.

  When the eighth speed is established, the first wet multi-plate clutch C1 is engaged, and the second wet multi-plate brake B2 and the fourth wet multi-plate brake B4 are fixed. As a result, the second coupling body Ca-Rc-Rd and the sun gear Sa (third element) of the first planetary gear mechanism 4 rotate at the same speed, and the first to third elements Sa of the first planetary gear mechanism 4 are rotated. , Ca and Ra are in a locked state where relative rotation is impossible. Thereby, the rotational speed of 1st coupling body Ra-Cb and 2nd coupling body Ca-Rc-Rd becomes "1".

  Further, the rotational speed of the fourth connected body Rb-Cc is “0”, and the rotational speed of the third connected body Sb-Sd is i + 1. Then, the rotational speed of the carrier Cd (11th element) of the fourth planetary gear mechanism 7 connected to the output member 3 becomes “8th” ((i + k + 1) / (k + 1)) shown in FIG. Established.

  When the reverse gear is established, the second wet multi-plate brake B2 and the third wet multi-plate brake B3 are set in a fixed state. Since the fourth wet multi-plate brake B4 is in the released state, the function of the one-way clutch F1 becomes invalid, and the first connected body Ra-Cb is allowed to reversely rotate.

  Further, since the rotational speeds of the fourth connected body Rb-Cc and the sun gear Sc (seventh element) of the third planetary gear mechanism 6 are “0”, the seventh to ninth elements Sc of the third planetary gear mechanism 6 are used. , Cc, Rc are in a locked state where relative rotation is impossible, and the rotation speed of the second coupling body Ca-Rc-Rd becomes "0". Then, the rotational speed of the carrier Cd (11th element) of the fourth planetary gear mechanism 7 connected to the output member 3 becomes “Rvs” of the reverse rotation shown in FIG. 2, and the reverse gear is established.

  A speed line indicated by a dotted line in FIG. 2 represents that each element of the other planetary gear mechanism rotates following the planetary gear mechanism that transmits power among the four planetary gear mechanisms 4 to 7.

  FIG. 3A is a diagram collectively showing the relationship between the above-described shift speeds and the states of the clutches C1 and C2 and the brakes B1 to B4 and the one-way clutch F1 that are the respective engagement mechanisms. And “◯” in the columns of the brakes B1 to B4 indicate a connected state or a fixed state. Further, “◯” in the column of the 1-way clutch F1 indicates that the rotation speed of the first coupling body Ra-Cb is “0” due to the action of the 1-way clutch F1. Further, “(◯)” in the column of the first wet multi-plate brake B1 indicates that the engine brake is fixed when it is applied.

  3B, the gear ratio h of the first planetary gear mechanism 4 is 1.666, the gear ratio i of the second planetary gear mechanism 5 is 1.666, and the gear ratio j of the third planetary gear mechanism 6 is the same. FIG. 3 (a) also shows the gear ratio of each gear stage (the rotational speed of the input shaft 2 / the rotational speed of the output member 3) when the gear ratio k of the fourth planetary gear mechanism 7 is 3.333. Yes. According to this, the public ratio (ratio of gear ratios between the gears) becomes appropriate, and the ratio orange (1st speed ratio / 8th speed ratio) shown in FIG. 3B is also appropriate.

  According to the automatic transmission of the embodiment, it is possible to perform eight forward shifts. In addition, from the fourth forward speed to the eighth forward speed, three engagement mechanisms out of a total of six engagement mechanisms of the two wet multi-plate clutches C1 and C2 and the four wet multi-plate brakes B1 to B4 are engaged. Will do. In addition, from the first forward speed to the third forward speed, the ring gear Ra (third element) of the first planetary gear mechanism 4 is operated by the one-way clutch F1 even if the first wet multi-plate brake B1 is in the released state. Since the rotational speed is “0”, no friction loss occurs in the first wet multi-plate brake B1.

  Therefore, the number of engagement mechanisms in which friction loss occurs at each gear speed except the reverse speed is three, as compared to the conventional mechanism in which four engagement mechanisms generate friction loss at each gear speed, Friction loss due to the open engagement mechanism can be reduced, and the transmission efficiency of the automatic transmission is improved.

  Further, on the axis of the input shaft 2 (or a main shaft (not shown) that rotatably supports the input shaft 2), a total of six planetary gear mechanisms 4 to 7 and two wet multi-plate clutches C1 and C2 are provided. Two members are arranged. For this reason, the shaft length of the automatic transmission is shortened as compared with the conventional product in which a total of seven members including three planetary gear mechanisms and four wet multi-plate clutches are arranged on the axis of the input shaft 2. It is possible to improve the mountability to a vehicle (particularly, FF type vehicle).

  Further, since all of the first to fourth planetary gear mechanisms 4 to 7 are constituted by a single pinion type planetary gear mechanism, each planetary gear mechanism 4 to 7 meshes with the sun gear and the ring gear and Compared to the case of a planetary gear mechanism of a double pinion type comprising a pair of pinions that mesh with the sun gear and the other mesh with the ring gear, and a carrier that rotatably and revolves, the input shaft 2 to the output member 3 The number of gear engagements in the power transmission path can be reduced, and transmission efficiency can be improved.

  In the automatic transmission of the embodiment, the effects of the above-described embodiment can be obtained even if the fourth wet multi-plate brake B4 and the one-way clutch F1 are omitted. In this case, the first wet multi-plate brake B1 may be fixed from the first forward speed to the third forward speed.

  If the fourth wet multi-plate brake B4 and the 1-way clutch F1 are omitted as described above, the first wet multi-plate brake B1 is released when upshifting from the third speed to the fourth speed. In addition to switching to the state, it is necessary to switch the second wet multi-plate brake B2 to the fixed state. Further, when downshifting from the fourth speed stage to the third speed stage, it is necessary to switch the first wet multi-plate brake B1 to a fixed state and switch the second wet multi-plate brake B2 to an open state.

  In the automatic transmission according to the embodiment, when upshifting from the third speed to the fourth speed, it is only necessary to switch the second wet multi-plate brake B2 to a fixed state, and to reduce the speed from the fourth speed to the third speed. When shifting, it is only necessary to switch the second wet multi-plate brake B2 to the open state.

  Therefore, according to the automatic transmission of the embodiment, the fourth wet multi-plate brake B4 and the one-way clutch F1 are omitted, and the first and second gears are shifted during the shift between the third speed and the fourth speed. The controllability of shifting between the third speed stage and the fourth speed stage can be improved as compared with the case where it is necessary to switch the states of the two wet multi-plate brakes B1, B2.

  In addition, the first wet multi-plate brake B1 of the embodiment can be switched to a fixed state only when the engine brake is applied at the first to third gears, and thus is configured with a wet multi-plate brake having a relatively small capacity. be able to.

  Here, in the wet multi-plate brake, the friction loss generated in the open state increases in proportion to the increase in capacity. For this reason, according to the automatic transmission of the embodiment, compared with the one that requires the use of a wet multi-plate brake having a relatively large capacity, the first to eighth gears at which the first connected body Ra-Cb rotates in the forward direction. The friction loss generated in the first wet multi-plate brake B1 can be reduced, and the transmission efficiency can be further improved.

  In the embodiment, the first wet multi-plate brake B1 is used as the first brake of the present invention. However, the first brake of the present invention is not limited to this. For example, a meshing mechanism such as a dog clutch or a synchromesh mechanism, A two-way clutch may be used. If comprised in this way, the friction loss in a 1st brake can be suppressed more in the forward 4th speed level-8th speed level in which a 1st brake will be in an open state, and the transmission efficiency of an automatic transmission will be improved more. be able to.

  When a two-way clutch is used as the first brake, a reverse rotation prevention state in which forward rotation (rotation in the direction in which the vehicle moves forward) is allowed and reverse rotation (rotation in the direction in which the vehicle moves backward) is prevented in the forward gear. In the reverse stage, it is sufficient to switch to a forward rotation prevention state that prevents forward rotation and allows reverse rotation. In this case, the 1-way clutch F1 and the fourth wet multi-plate brake B4 can be omitted.

  According to this, the controllability of the shift between the third speed and the fourth speed can be improved for the same reason as when the 1-way clutch F1 of the automatic transmission according to the embodiment is used. The two-way clutch is a friction loss even when the ring gear Ra (third element) of the first planetary gear mechanism 4 is fixed to the transmission case 1 in an open state (in the embodiment, the fourth speed to the eighth speed). Does not occur. For this reason, the friction loss can be further suppressed as the entire automatic transmission. Further, when the vehicle is in a decelerating state at the first to third forward speeds, the engine brake can be applied by switching the two-way clutch to the forward rotation preventing state.

  In the embodiment, the first to fourth planetary gear mechanisms 4 to 7 are configured by a single pinion type planetary gear mechanism. However, the first to fourth planetary gear mechanisms 4 to 7 are configured by a double pinion type planetary gear mechanism. May be.

DESCRIPTION OF SYMBOLS 1 ... Transmission case, 2 ... Input shaft, 3 ... Output member, 4 ... 1st planetary gear mechanism, Sa ... Sun gear (3rd element), Ra ... Ring gear (1st element), Pa ... Pinion, Ca ... Carrier (1st) 2 elements), 5 ... second planetary gear mechanism, Sb ... sun gear (fourth element), Rb ... ring gear (sixth element), Pb ... pinion, Cb ... carrier (fifth element), 6 ... third planetary gear mechanism, Sc ... sun gear (seventh element), Rc ... ring gear (ninth element), Pc ... pinion, Cc ... carrier (eighth element), 7 ... fourth planetary gear mechanism, Sd ... sun gear (tenth element), Rd ... ring gear ( 12th element), Pd ... pinion, Cd ... carrier (11th element), C1 ... first wet multi-plate clutch (first clutch), C2 ... second wet multi-plate clutch (second clutch), B1 ... first Wet multi-plate brake (first brake), B2 ... Second wet multi-plate brake (second brake), B3 ... Third wet multi-plate brake (third brake), B4 ... Fourth wet multi-plate brake (fourth brake) ), F1 ... 1-way clutch.

Claims (4)

An automatic transmission that is rotatably supported in a transmission case and that rotates the input shaft rotated by power from a drive source in multiple stages and outputs it from an output member,
There are provided first to fourth planetary gear mechanisms each having three elements including a sun gear, a carrier, and a ring gear,
The three elements of the first planetary gear mechanism are a first element, a second element, and a third element, respectively, in order of arrangement at intervals corresponding to the gear ratio in the velocity diagram,
The three elements of the second planetary gear mechanism are a fourth element, a fifth element, and a sixth element, respectively, in order of arrangement at intervals corresponding to the gear ratio in the velocity diagram,
The three elements of the third planetary gear mechanism are a seventh element, an eighth element, and a ninth element, respectively, in order of arrangement at intervals corresponding to the gear ratio in the velocity diagram,
The three elements of the fourth planetary gear mechanism are respectively arranged as a tenth element, an eleventh element, and a twelfth element in order of arrangement at intervals corresponding to the gear ratio in the velocity diagram.
The third element is connected to the input shaft, the eleventh element is connected to the output member,
The first element and the fifth element are connected to form a first connecting body, the second element, the ninth element, and the 12 element are connected to form a second connecting body, and the first element Connecting the four elements and the tenth element to form a third connected body, connecting the sixth element and the eighth element to form a fourth connected body,
A first clutch that is switchable between a connected state that connects the second connecting body and the third element of the first planetary gear mechanism, and an open state that cuts off the connection;
A second clutch that is switchable between a connected state that connects the second connected body and the third connected body, and an open state that cuts off the connection;
A first brake switchable between a fixed state for fixing the first coupling body to the transmission case and an open state for releasing the fixing;
A second brake that is switchable between a fixed state in which the fourth connecting body is fixed to the transmission case and an open state in which the fixing is released;
An automatic transmission comprising: a third brake switchable between a fixed state in which a seventh element of the third planetary gear mechanism is fixed to the transmission case and an open state in which the fixation is released. The automatic transmission according to claim 1, wherein
A one-way clutch that rotates integrally with the first connecting body is provided only when the first connecting body reverses,
4. An automatic transmission comprising a fourth brake capable of switching between a fixed state in which the one-way clutch is fixed to the transmission case and an open state in which the fixing is released. The automatic transmission according to claim 1, wherein
The first brake includes a dog clutch or a reverse rotation preventing state in which forward rotation of the first connecting body is permitted and reverse rotation is prevented, and a forward rotation blocking state in which forward rotation of the first connecting body is prevented and reverse rotation is allowed. An automatic transmission comprising a two-way clutch that can be switched freely. The automatic transmission according to any one of claims 1 to 3,
The four planetary gear mechanisms are constituted by a single pinion type planetary gear mechanism including a sun gear, a ring gear, and a carrier that rotatably and revolves a pinion that meshes with the sun gear and the ring gear. Automatic transmission.

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